Lakebed Temple - Piece of Heart Locations
Just like basically every other dungeon in Twilight Princess, Lakebed Temple houses two different heart pieces for you to obtain. The first one is found about half way through the dungeon as you're changing the water levels back and forth. The second piece of heart is found at the end of the dungeon after you flood the main room.
Lakebed Temple - First Piece of Heart
For this piece of heart you have to restore water to both the east and west sides in Lakebed Temple. After you do that you'll want to turn the stairs to the lower east side if you're on the Gamecube or west side if you're on the Wii.
Essentially what you want to do is have water flow into one of the rooms we visited earlier in the dungeon, the same room that had two geysers, vines to climb on and spinning platforms. Bringing water to this room will raise the bridge that's found here allowing access to a chest in the southern portion of the room.
But wait ... there's more! This chest is deviously placed behind a closed door - however - there's a switch on the floor nearby. As seen in my screen shots above when you stand on the switch the door will open. Do this and Clawshot into the room to grab the treasure chest.
Lakebed Temple - Second Piece of Heart
The second piece of heart in Lakebed Temple is much easier to grab than the first one. This one is found in the main room of the temple where we adjusted the water flow for the entire dungeon. If you look up at the chandelier (as seen in my first screen shots) you'll notice claw shot locations on it.
Yup, you guessed it! Clawshot to the chandelier and grab the chest ontop of it. That's all there is to this piece of heart!